Rigid conduit, made from metal or plastic, is commonly employed by electricians in commercial, industrial, and, occasionally, residential structures. Such conduit may be selected by the electrician for easy of use, flexibility in future expansion, or such conduit may be required by electrical codes.
The construction of rigid conduit has been standardized to enable components from different manufacturers to be utilized together and also so that standardized tools may be used in assembly and construction. Conduit includes pipes and fittings, as well as other components. Fittings may be used, for example, to connect lengths of pipes together, to allow access to internal wires after assembly, or to facilitate changes in direction of a wire run.
A 90 degree turn in the conduit may be accomplished by fittings such as, for example, an “LB” fitting—so named because of the “el” shape of the fitting and the location of the conduit exit point on the “back” of the fitting. However, the use of an LB fitting requires at least two electricians to pull wire through a length of conduit—a first electrician to pull the wire, and a second electrician to guide the wire around the sharp angle of the LB fitting. Even if the first electrician could apply enough pulling force to the wire, an unacceptable amount of damage would likely be done to the wire.
Previous devices have attempted to address the difficulties in wire pulling but have not been able to address both the need for two electricians and the need to avoid damage to wire. Some prior art devices provide guide rollers to prevent contact between the wire and the fitting edges. However, such devices still require a second electrician to guide the wire through the fitting. See U.S. Pat. Nos. 3,020,332 and 3,944,184.
Other prior art devices provide rollers or pulleys that are temporarily seated within the fitting to guide the wire through. Such devices may alleviate the need for a second electrician because the roller allows the wire to pass through the fitting without assistance. However, these prior art devices suffer from a small size of the roller used. Wire pulled through such a device may not be damaged by contact with the sharp edges of the fitting, but may still be damaged by the act of being pulled around a roller of insufficient radius. Such damage is readily apparent when the wire being pulled is an optical fiber cable in which one or more glass fibers within the cable must not be bent around a radius below a certain threshold. See, e.g., U.S. Pat. No. 4,909,481.
As exemplified by the aforementioned prior art devices, such device should be temporarily adapted to the conduit fitting so that when the wire has been pulled through, the device may be removed and a cover may be affixed to the fitting.
Accordingly, there is a need for a device which may be temporarily adapted to an conduit fitting, and which eliminates the need for a second electrician without causing an unacceptable amount of damage to the wire.